In the past year, platelet and granulocyte support of alloimmunized patients has improved considerably as a result of the creation of a HLA typed donor file. Analysis of these transfusions is in progress in an attempt to determine the relative antigenicity of different cross-reactive HLA antigens and to define certain paterns of alloimmunization. HLA matched platelets have also been cryopreserved using DMSO, and in particular a large number of frozen autologus platelet transfusions obtained from patients in leukemia have been administered with in vivo recoveries of between 50-60%. Ultrastructural studies of the frozen platelets and a model system which measures release of LDH are being utilized to improve upon these results. We have continued to administer granulocytes as early in the course of the infectious illness as possible and have accumulated further evidence of the efficacy of granulocyte transfusion. A protocol studying the prophylactic use of granulocyte trasfusion which will also study certain aspects of the alloimmunization process will also be implemented. Experiments designed to improve elution of the granulocytes from nylon fibers have been carried out. Anaesthetic agents are capable of reversing granulocyte adherence to fibers and, under the proper conditions, do not cause significant, irreversible damage to the granulocytes. Studies about the effect of these drugs on platelet function as well as studies on corticosteroid related changes in platelet function are in progress. BIBLIOGRAPHIC REFERENCES: Rubin, R. and Schiffer, C.A.: Fate in humans of the plasticizer di (2-ethylhexyl) phthalate, arising from transfusion of platelets stored in vinyl plastic bags. Transfusion 16: 330-335, 1976. Sciffer, C.A., Buchholz, D.H., Aisner, J., Wolff, J.H. and Wiernik, P.H.: Frozen autologous platelets in the supportiie care of patients with leukemia. Transfusion 16: 321-329, 1976.